Provided by: btrbk_0.26.0-1_all bug

NAME

       btrbk - backup tool for btrfs subvolumes

SYNOPSIS

       btrbk [-h|--help] [--version]
             [-c|--config <file>] [-n|--dry-run]
             [-p|--preserve] [--preserve-snapshots] [--preserve-backups]
             [-v|--verbose] [-q|--quiet] [-l|--loglevel <level>]
             [-t|--table] [--format <output-format>]
             [--progress] [--print-schedule]
             [--override <config_option>=<value>]
             [--lockfile <file>]
             <command> [<args>]

DESCRIPTION

       btrbk is a backup tool for btrfs subvolumes, taking advantage of btrfs specific
       capabilities to create atomic snapshots and transfer them incrementally to a target btrfs
       filesystem. It is able to perform backups from one source to multiple destinations.

       Snapshots as well as backup subvolume names are created in form:

           <snapshot-name>.<timestamp>[_N]

       Where <snapshot-name> is identical to the source subvolume name, unless the configuration
       option snapshot_name is set. The <timestamp> is either "YYYYMMDD" or "YYYYMMDDThhmm"
       (dependent of the timestamp_format configuration option), where "YYYY" is the year, "MM"
       is the month, "DD" is the day, "hh" is the hour and "mm" is the minute of the creation
       time (local time of the host running btrbk). If multiple snapshots/backups are created on
       the same date/time, N will be incremented on each snapshot, starting at 1.

OPTIONS

       -h, --help
           Prints the synopsis and a list of the commands.

       --version
           Prints the btrbk version.

       -n, --dry-run
           Don’t run anything that would alter the filesystem, just show the snapshots and backup
           subvolumes that would be created/deleted by the run, snapshot, resume, prune, archive
           and clean commands. Use in conjunction with -l debug to see the btrfs commands that
           would be executed.

       -c, --config <file>
           Read the configuration from <file>.

       -p, --preserve
           Preserve all snapshots and backups. Skips deletion of any snapshots and backups, even
           if specified in the configuration file (shortcut for "--preserve-snapshots
           --preserve-backups").

       --preserve-snapshots
           Preserve all snapshots. Skips deletion of any snapshots, even if specified in the
           configuration file.

       --preserve-backups
           Preserve all backups. Skips deletion of any backups, even if specified in the
           configuration file.

       --wipe
           Ignore configured snapshot retention policy, delete all but latest snapshots instead.
           All snapshots needed for incremental backup (latest common) are also preserved. Useful
           if you are getting low on disk space (ENOSPC).

       -v, --verbose
           Verbose output (shortcut for "--loglevel=info").

       -q, --quiet
           Quiet operation. If set, btrbk does not print the summary after executing the run,
           snapshot, resume, prune, or archive commands.

       -l, --loglevel <level>
           Set the level of verbosity. Accepted levels are warn, info, debug, and trace.

       -t, --table
           Print output in table format (shortcut for "--format=table").

       --format table|long|raw
           Print output in specified format. If set to "raw", prints space-separated key="value"
           pairs (machine readable). Affects output format for run, snapshot, resume, prune,
           archive and list commands. Useful for further exporting/scripting.

       --progress
           Show progress bar on send-receive operation.

       --print-schedule
           Print detailed scheduler information on run, snapshot, resume, prune and archive
           commands. Use the --format command line option to switch between different output
           formats.

       --lockfile <file>
           Create lockfile <file> on startup; checks lockfile before running any btrfs commands
           (using perl "flock"), and exits if the lock is held by another btrbk instance.
           Overrides configuration option "lockfile". Ignored on dryrun (-n, --dry-run).

       --override <config_option>=<value>
           Override a configuration option <config_option> with <value>. Globally, for ALL
           contexts. Use with care!

COMMANDS

   Actions
       The following commands are used to create snapshots and/or backups. All actions can
       operate in dry-run mode (-n, --dry-run). Use the --format command line option to switch
       between different output formats.

       See section RETENTION POLICY in btrbk.conf(5) for information on configuring the retention
       policy.

       run [filter...]
           Perform snapshot and backup operations as specified in the configuration file. If the
           optional [filter...] arguments are present, snapshots and backups are only performed
           for the subvolumes/targets matching a filter statement (see FILTER STATEMENTS below).

           Step 0: Read Data
               Read information from the source and target btrfs filesystems in order to perform
               sanity checks and identify parent/child and received-from relationships.

           Step 1: Create Snapshots
               If the checks succeed, btrbk creates snapshots for the source subvolumes specified
               in the configuration file, according to the snapshot_create option.

           Step 2: Create Backups
               For each specified target, btrbk creates the backups as follows: After comparing
               the backups to the source snapshots, btrbk transfers all missing snapshots needed
               to satisfy the configured target retention policy, incrementally from the latest
               common parent subvolume found. If no common parent subvolume is found (or if the
               incremental option is set to “no”), a full (non-incremental) backup is created.

           Step 3: Delete Backups
               Unless the -p, --preserve or --preserve-backups option is set, backup subvolumes
               that are not preserved by their configured retention policy will be deleted. Note
               that the latest snapshot/backup pair are always preserved, regardless of the
               retention policy.

           Step 4: Delete Snapshots
               Unless the -p, --preserve or --preserve-snapshots option is set, snapshots that
               are not preserved by their configured retention policy will be deleted. Note that
               the latest snapshot (the one created in step 1) as well as the latest
               snapshot/backup pair are always preserved, regardless of the retention policy.

       dryrun [filter...]
           Don’t run any btrfs commands that would alter the filesystem, just show the snapshots
           and backup subvolumes that would be created/deleted by the run command. Use in
           conjunction with -l debug to see the btrfs commands that would be executed.

       snapshot [filter...]
           Snapshot only: skips backup creation and deletion (steps 2 and 3). Use in conjunction
           with -p, --preserve (or --preserve-snapshots) if you also want to skip snapshot
           deletion (step 4).

       resume [filter...]
           Resume backups: skips snapshot creation (step 1), transfers and deletes
           snapshots/backups in order to satisfy their configured retention policy. Use in
           conjunction with -p, --preserve, --preserve-backups, --preserve-snapshots if you want
           to skip backup and/or snapshot deletion (steps 3, 4).

       prune [filter...]
           Prune snapshots and backups: skips snapshot and backup creation (steps 1, 2), only
           deletes snapshots and backups in order to satisfy their configured retention policy.
           Useful for cleaning the disk after changing the retention policy. Use in conjunction
           with --preserve-backups, --preserve-snapshots if you want to skip backup or snapshot
           deletion (steps 3, 4).

       archive <source> <target> *experimental*
           Recursively copy all subvolumes created by btrbk from <source> to <target> directory,
           optionally rescheduled using archive_preserve_* configuration options. Also creates
           directory tree on <target> (see bugs below). Useful for creating extra archive copies
           (clones) from your backup disks. Note that you can continue using btrbk after swapping
           your backup disk with the archive disk.

           Note that this feature needs a linux kernel >=4.4 to work correctly! Kernels >=4.1 and
           <4.4 have a bug when re-sending subvolumes (the archived subvolumes will have
           incorrect received_uuid, see
           http://thread.gmane.org/gmane.comp.file-systems.btrfs/48798), so make sure you run a
           recent kernel.

           Known bugs: If you want to use nested subvolumes on the target filesystem, you need to
           create them by hand (e.g. by running "btrfs subvolume create <target>/dir"). Check the
           output of --dry-run if unsure.

       clean [filter...]
           Delete incomplete (garbled) backups. Incomplete backups can be left behind on network
           errors or kill signals while a send/receive operation is ongoing, and are identified
           by the "received_uuid" flag not being set on a target (backup) subvolume.

       The following table gives a quick overview of the action commands and resulting snapshot
       creation (S+), backup creation (B+), snapshot deletion (S-), and backup deletion (B-):

           Command   Option                 S+ B+ S- B-
           --------------------------------------------
           run                              x  x  x  x
           run       --preserve             x  x
           run       --preserve-snapshots   x  x     x
           run       --preserve-backups     x  x  x
           snapshot                         x     x
           snapshot  --preserve             x
           resume                              x  x  x
           resume    --preserve                x
           resume    --preserve-snapshots      x     x
           resume    --preserve-backups        x  x
           prune                                  x  x
           prune     --preserve-snapshots            x
           prune     --preserve-backups           x

   Informative Commands
       The following commands are informative only, and will not alter the file system.

       stats [filter...]
           Print statistics of snapshot and backup subvolumes. Optionally filtered by [filter...]
           arguments (see FILTER STATEMENTS below).

       list <subcommand> [filter...]
           Print information defined by <subcommand> in a tabular form. Optionally filtered by
           [filter...] arguments (see FILTER STATEMENTS below).

           Available subcommands:

           snapshots
               List all snapshots (and corresponding backups).

           backups
               List all backups (and corresponding snapshots).

           latest
               List most recent common snapshot/backup pair, or most recent snapshot if no common
               found.

           config
               List configured source/snapshot/target relations.

           source
               List configured source/snapshot relations.

           volume
               List configured volume sections.

           target
               List configured targets.

           Use the --format command line option to switch between different output formats.

       usage [filter...]
           Print filesystem usage information for all source/target volumes, optionally filtered
           by [filter...] arguments (see FILTER STATEMENTS below). Note that the "free" value is
           an estimate of the amount of data that can still be written to the file system.

       origin <subvolume>
           Print the subvolume origin tree: Shows the parent-child relationships as well as the
           received-from information. Use the --format command line option to switch between
           different output formats.

       diff <from> <to>
           Print new files since subvolume <from> for subvolume <to>.

       config print|print-all
           Prints the parsed configuration file. Use the --format command line option to switch
           between different output formats.

FILTER STATEMENTS

       Filter arguments are accepted in form:

       <group-name>
           Matches the group configuration option of a volume, subvolume or target section.

       [hostname:]<volume-directory>
           Matches all subvolumes and targets of a volume configuration section.

       [hostname:]<volume-directory>/<subvolume-name>
           Matches the specified subvolume and all targets of a subvolume configuration section.

       [hostname:]<target-directory>
           Matches all targets of a target configuration section.

       [hostname:]<target-directory>/<snapshot-name>
           Matches a single target of a target section within a subvolume section with given
           <snapshot-name>.

       For convenience, [hostname:] can be specified as either "hostname:" or "ssh://hostname/".

FILES

       /etc/btrbk.conf, /etc/btrbk/btrbk.conf
           Default configuration file. The file format and configuration options are described in
           btrbk.conf(5).

EXIT STATUS

       btrbk returns the following error codes:

       0
           No problems occurred.

       1
           Generic error code.

       2
           Parse error: when parsing command-line options or configuration file.

       3
           Lockfile error: if lockfile is present on startup.

       10
           Backup abort: At least one backup task aborted.

       255
           Script error.

AVAILABILITY

       Please refer to the btrbk project page https://digint.ch/btrbk/ for further details.

SEE ALSO

       btrbk.conf(5), btrfs(8)

       For more information about btrfs and incremental backups, see the web site at
       https://btrfs.wiki.kernel.org/index.php/Incremental_Backup

AUTHOR

       Axel Burri <axel@tty0.ch>